The effect of orlistat, an inhibitor of dietary fat absorption, on the absorption of vitamins A and E in healthy volunteers

Exercise Training as an Adjunct to Orlistat Therapy Reduces Oxidative Stress in Obese Subjects

The anti-obesity drug orlistat promotes weight loss and improves obesity-related risk factors, but its effect on oxidative stress is not clear yet. Orlistat reduces dietary fat absorption, which may have effects on fat soluble vitamins especially the antioxidant vitamins A and E. The aim of this study was to determine and compare the effects of weight loss achieved by orlistat therapy and a combination of orlistat with aerobic exercise training on lipid peroxidation and antioxidative defense in obese subjects. Total of 24 obese subjects were randomly assigned to receive 12-week treatment with hypocaloric diet-orlistat (120 mg three times daily) (DO group) or diet-orlistat-exercise (DOE group). Serum levels of malondialdehyde (MDA), a marker for lipid peroxidation, and vitamins A and E were measured by high performance liquid chromatography at baseline and at the end of the treatment. Body weight and fat mass were significantly reduced in the two groups (p < 0.001). In the DO group, the MDA levels remained unchanged (p = 0.59), while vitamins A (p < 0.01) and E (p < 0.001) were significantly decreased. In contrast, the subjects treated with DOE exhibited marked decreases in MDA (p = 0.002) and a small but significant decrease in vitamins A (p = 0.003) and E (p = 0.003). Thus, orlistat therapy alone caused a significant reduction in antioxidative capacity without affecting oxidative stress, whereas orlistat in combination with exercise training provided a significant decrease in MDA levels. The beneficial effect of aerobic exercise as an adjunct to the orlistat therapy is of importance with regard to the obesity-associated risk factors.

Psychiatric medication-induced obesity: treatment options

A majority of psychiatric medications are known to generate weight gain and ultimately obesity in some patients. The authors undertook a comprehensive literature review in order to provide a better understanding of novel treatment options in regards to alleviating weight gained by use of antidepressants, antipsychotics, and mood stabilizers. There are no agents for management of this weight gain approved by the Food and Drug Administration (FDA), and existing studies on options are mainly uncontrolled, small-scale projects with limited power to produce coherent conclusions. There is a clear need for larger studies on existing options, and future psychotropics without these side-effects are currently in the pipeline.

Effects of orlistat, a lipase inhibitor, on the pharmacokinetics of three highly lipophilic drugs (amiodarone, fluoxetine, and simvastatin) in healthy volunteers

To investigate the effect of orlistat on the pharmacokinetics of three highly lipophilic drugs (amiodarone, fluoxetine, and simvastatin), the authors performed double-blind, placebo-controlled, randomized two-period crossover (for fluoxetine and simvastatin) or parallel (for amiodarone) studies in healthy volunteers ages 18 to 65 years of a body mass index between 18 and 30 kg/m2. During treatment with orlistat or matching placebo for 5 to 13 1/3 days, a single oral dose of highly lipophilic drug was administered, followed by obtaining serial blood samples for measuring plasma (for fluoxetine and simvastatin) or serum (for amiodarone) concentrations of the lipophilic drug and its active metabolite. Treatments were compared for the pharmacokinetic parameters AUC0-infinity, Cmax, tmax, and t 1/2 of highly lipophilic drugs and active metabolites. Analysis of variance was performed to assess the significance of the sequence effect and provide the variance estimate for the 90% confidence intervals. Subjects were also evaluated for adverse events, vital signs, and clinical and laboratory safety. The absorption of amiodarone (and active metabolite) was significantly reduced by approximately one-quarter using parameters of Cmax and AUC, while no inhibition of absorption was observed for fluoxetine and simvastatin as well as their active metabolites. There were no clinically significant differences in t 1/2 and tmax for all three drugs tested. Due to expected gastrointestinal adverse events known to occur with orlistat, there was a higher incidence of adverse events under regimen B (highly lipophilic drugs and orlistat) than under regimen A (highly lipophilic drugs and placebo). Other adverse events were sporadic and unremarkable. There were no clinically relevant changes in vital signs or laboratory values. In conclusion, except for amiodarone, there was no effect of orlistat on the pharmacokinetics of highly lipophilic drugs when these drugs were taken concomitantly with orlistat.

Orlistat use in type 2 diabetes

OBJECTIVE

To review the use of orlistat in type 2 diabetes.

DATA SOURCES

A MEDLINE search of the English-language literature (1990-August 2001) was performed using the key terms orlistat, obesity, glucose, and diabetes.

DATA EXTRACTION

All articles pertaining to orlistat were considered for inclusion, with emphasis placed on randomized, placebo-controlled, double-blind clinical trials.

DATA SYNTHESIS

In April 1999, orlistat was approved by the Food and Drug Administration for the treatment of obesity. Of 13 randomized, placebo-controlled studies, only 2 reported specific data in individuals with type 2 diabetes. Both reported significant weight reduction and improved glycemic control over placebo.

CONCLUSIONS

Since weight loss is a difficult goal to achieve in patients with type 2 diabetes, orlistat can be a safe, effective addition to a multidisciplinary approach.

Effects of orlistat on fat-soluble vitamins in obese adolescents

STUDY OBJECTIVES

To determine whether orlistat causes fat-soluble vitamin deficiencies in African-American and Caucasian adolescents.

DESIGN

Prospective, open-label pilot study.

SETTING

Warren Grant Magnuson Clinical Center of the National Institutes of Health.

PATIENTS

Seventeen adolescents with body mass indexes above the 95th percentile for age, race, and gender who also had at least one obesity-related comorbid condition.

INTERVENTION

Subjects received orlistat 120 mg 3 times/day and a daily multivitamin supplement containing vitamin A 5000 IU, vitamin D 400 IU, vitamin E 300 IU, and vitamin K 25 microg.

MEASUREMENTS AND MAIN RESULTS

During 3-6 months of orlistat treatment, acute absorption of retinol (vitamin A) was not significantly altered, but absorption of alpha-tocopherol (vitamin E) was significantly reduced compared with baseline levels (p<0.001). Serum levels of vitamins A and E did not change significantly; however, there was a nonsignificant decrease in vitamin K. Mean vitamin D levels were significantly reduced compared with baseline (p<0.02) after 1 month of orlistat, despite multivitamin supplementation.

CONCLUSION

It may be prudent to monitor vitamin D concentrations in adolescents who take orlistat, even when a multivitamin is prescribed.

Sciatic nerve lipoprotein lipase is reduced in streptozotocin-induced diabetes and corrected by insulin

The metabolic abnormalities underlying the cause of diabetic neuropathy have been the subject of much debate. Lipoprotein lipase (LPL) is a 56-kDa enzyme produced by several tissues in the body and has recently been shown in vitro to be expressed in cultured Schwann cells, where it is important in phospholipid synthesis. This suggests a role for LPL in myelin biosynthesis in the peripheral nervous system. The aim of this study was to determine if acute streptozotocin (STZ)-induced diabetes reduces the expression and regulation of sciatic nerve LPL in vivo. Adult Sprague Dawley rats were rendered diabetic via an sc injection of STZ. A decrease in sciatic nerve LPL activity was observed in the STZ-treated rats after just 2 d of diabetes and remained significantly reduced for at least 35 d. The decrease in LPL activity coincided temporally with a drop in motor nerve conduction velocity. Treatment with insulin for 4 d showed a normalization of sciatic nerve LPL activity. These results show that STZ-induced diabetes causes a decrease in LPL activity in the sciatic nerve that, as in other tissues, is reversible with insulin treatment. These data may suggest a role for LPL in the pathophysiology of diabetic neuropathy.

Obesity in transplant patients: case report showing interference of orlistat with absorption of cyclosporine and review of literature

OBJECTIVE

To report a case of an obese patient who had undergone renal transplantation and who had subtherapeutic levels of serum cyclosporine after treatment with orlistat.

METHODS

The clinical and laboratory findings are presented, and the few cases reported in the literature are reviewed.

RESULTS

A 29-year-old woman had subtherapeutic plasma levels of cyclosporine after orlistat treatment (360 mg/day) was initiated. The subtherapeutic levels persisted even though orlistat was administered the recommended 2 hours before ingestion of cyclosporine and even though the dosage of orlistat was decreased to only 240 mg/day. Because an increase of body weight is common after organ transplantation, treatment with orlistat has been used. In such patients, however, six cases of reduced therapeutic plasma levels of cyclosporine have been reported. Although a drug-drug interaction has been suggested, this case suggests that the decreased plasma cyclosporine levels are due to reduced absorption of fats rather than a drug-drug interaction. Because this patient was unable to adhere to a low-fat diet, she experienced severe diarrhea, a factor that may have dramatically diminished the absorption of cyclosporine.

CONCLUSION

Adherence to a low-fat diet should be strongly recommended if orlistat is prescribed to patients taking cyclosporine. Moreover, strict surveillance of the plasma concentration of cyclosporine is important.

The effect of orlistat on plasma levels of psychotropic drugs in patients with long-term psychopharmacotherapy

Weight gain induced by long-term psychopharmacotherapy has emerged as a relevant clinical issue because it is a major problem affecting compliance and long-term outcome. The novel antiobesity drug orlistat inhibits gastrointestinal lipases, thus lowering the absorption of dietary fat and raising the possibility of decreased absorption of fat-soluble vitamins and certain concomitantly administered drugs in some individuals. We monitored plasma levels of several psychotropic agents in eight psychiatric patients receiving orlistat to determine the potential influence of orlistat on the bioavailability of these drugs. We found no clinically relevant changes in plasma concentrations of haloperidol, clozapine, clomipramine, desipramine, or carbamazepine over an 8-week period in orlistat recipients. We therefore consider orlistat to be compatible with use during long-term pharmacotherapy. Our preliminary findings suggest that orlistat may offer a pharmacological treatment option to support dietary efforts in obese and overweight psychiatric patients. However, so far no data about the potential influence of orlistat on pharmacokinetics of psychotropics have been published; therefore, plasma level monitoring is recommended.

Orlistat--a novel weight loss therapy

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical safety and efficacy, drug interactions, and therapeutic issues related to the use of orlistat for treatment of obesity.

DATA SOURCES

English-language articles were identified from MEDLINE (1966-July 2000), Roche Laboratories, organizational guidelines, National Institutes of Health and Food and Drug Administration Web sites, and Doctor's Guide online. Key words included obesity, orlistat, and lipase inhibitors. References were also identified from reference sections of published articles.

STUDY SELECTION AND DATA EXTRACTION

Prospective, randomized, double-blind, placebo-controlled, human trials were selected for review and discussion.

DATA SYNTHESIS

Orlistat is the first agent in the lipase inhibitor class of antiobesity drugs. Orlistat is minimally absorbed and has been shown to reduce body weight by inhibiting absorption (by approximately 30%) of ingested dietary fat. Safety and efficacy have been established in one- and two-year double-blind, placebo-controlled trials; adverse effects were primarily, and almost exclusively, gastrointestinal. Due to its ability to block fat absorption, orlistat also has the capability to inhibit absorption of fat-soluble vitamins. Therefore, a daily multiple vitamin is recommended while taking orlistat.

CONCLUSIONS

By inhibiting fat absorption, orlistat offers a new treatment modality for weight loss and maintenance. Preliminary data from clinical trials suggest that orlistat may be beneficial in patients with comorbid conditions related to obesity, such as diabetes and hyperlipidemia. However, further studies during postmarketing surveillance are needed to fully establish orlistats long-term benefits and safety. Orlistat should be considered a useful adjunctive therapy for weight loss and maintenance in obese patients (i.e., body mass index > or = 30 kg/m2 or > or = 27 kg/m2 if other risk factors are present) committed to lifestyle changes including diet, exercise, and behavioral modification.

Weight gain from novel antipsychotic drugs: need for action

Obesity is common in schizophrenia, and people with schizophrenia appear to be at increased risk for certain obesity-related conditions, such as type 2 diabetes and cardiovascular disease. Antipsychotic drugs, used chronically to control symptoms of schizophrenia, are associated with often-substantial weight gain, a side effect that is a special concern with the latest generation of highly effective "novel" agents. That the most effective (e.g., novel) antipsychotic medications lead to substantial weight gain presents the field with a critical public health problem. Although preliminary data have been reported regarding the beneficial use of behavior therapy programs for short-term weight control in patients with schizophrenia, the available data are quite limited, and there are no data regarding the long-term beneficial effects of these programs in this population. The obesity field recently has developed programs emphasizing "lifestyle changes" (e.g., diet, exercise, and problem-solving skills) to successfully manage weight in patients without schizophrenia. Such programs can be adapted for patients with schizophrenia through the use of highly structured and operationalized modules emphasizing medication compliance, social skills development, and participation in outpatient programs. Moreover, these programs can potentially be combined with the use of adjunctive pharmacotherapy to maximize and maintain weight loss. The field must solve the paradox that some of our most effective medications for schizophrenia produce substantial weight gain and its associated troubling health risks.

Orlistat, a new lipase inhibitor for the management of obesity

Orlistat, a weight-loss agent with a novel mechanism of action, recently was approved by the Food and Drug Administration for the treatment of obesity. It inhibits gastric and pancreatic lipases in the lumen of the gastrointestinal tract to decrease systemic absorption of dietary fat. In several trials lasting up to 2 years, orlistat was more effective than diet alone for weight reduction and maintenance of lost weight. Orlistat treatment also results in modest improvements in total cholesterol, low-density lipoprotein, blood pressure, and fasting glucose and insulin concentrations. The major adverse effects are gastrointestinal, usually occur early in therapy, and tend to decrease with continued treatment. Because orlistat may decrease the absorption of fat-soluble vitamins, a standard multiple-vitamin supplement is recommended daily during therapy to prevent abnormalities in vitamin serum concentrations. The potential for severe gastrointestinal discomfort and the modest degree of weight loss may limit the agent's clinical utility. Its long-term safety and effectiveness for weight maintenance, cost-effectiveness of treatment, and overall reduction in obesity-related morbidity and mortality remain to be determined.

One-year treatment of obesity: a randomized, double-blind, placebo-controlled, multicentre study of orlistat, a gastrointestinal lipase inhibitor

OBJECTIVE

To assess the efficacy and tolerability of orlistat (Xenical) in producing and maintaining weight loss over a 12-month period.

DESIGN

Patients were randomized to double-blind treatment with either orlistat 120 mg or placebo three times daily, in conjunction with a low-energy diet, for 12 months.

SETTING

Five centres in the UK.

SUBJECTS

228 obese adult patients with body mass index between 30 and 43 kg/m2 and mean weight 97 kg (range 74-144 kg).

INTERVENTIONS

All patients were prescribed a low-energy diet, providing 30% of energy from fat, designed to produce an individually tailored energy deficit of approximately 600 kcal/day, for a run-in period of 4 weeks and then 12 months, plus orlistat 120 mg or placebo three times daily.

MAIN OUTCOME MEASURES

Change in body weight (the primary efficacy parameter), waist circumference and adverse events were reviewed regularly, together with serum lipids, insulin, glucose and plasma levels of fat-soluble vitamins and beta carotene.

RESULTS

Based on an intent-to-treat analysis, after 1 y of treatment patients receiving orlistat had lost an average of 8.5% of their initial body weight compared with 5.4% for placebo-treated patients; 35% of the orlistat group lost at least 5% of body weight compared with 21% of the placebo group (P < 0.05), and 28% and 17%, respectively (P = 0.04) lost at least 10% of body weight. Orlistat-treated patients showed significant decreases (P < 0.05) in serum levels of total cholesterol, low density lipoprotein cholesterol, and in the low density lipoprotein: high density lipoprotein ratio in comparison with placebo. Both groups had similar adverse-event profiles, except for gastrointestinal events, which were 26% more frequent in the orlistat group but were mostly mild and transient. To maintain normal plasma levels of fat-soluble vitamins, supplements of vitamins A, D and E were given to 1.8%, 8.0% and 3.6%, respectively, of orlistat-treated patients, compared with 0.9% of placebo-treated patients for each vitamin type. After 1 y, the decrease in vitamin E and beta carotene was significantly greater in orlistat-treated patients compared with those receiving placebo (P < 0.001). No significant change was found in the mean vitamin E:total cholesterol ratio in either group after 52 weeks.

CONCLUSIONS

Orlistat, in conjunction with a low-energy diet, produced greater and more frequent significant weight loss than placebo during 1 y of treatment. One-third of orlistat-treated patients achieved clinically relevant weight loss (> or = 5% initial body weight). There was also an improvement in relevant serum lipid parameters. Fat-soluble vitamin supplements may be required during chronic therapy. Orlistat was well tolerated and offers a promising new approach to the long-term management of obesity.

Mechanisms of vitamin E regulation: research over the past decade and focus on the future

This paper discusses the developments in human vitamin E research since 1990. New methodologies such as the use of stable isotopes, advances in vitamin E measurements, and isolation and cloning of specific alpha-tocopherol binding proteins have facilitated investigation of alpha-tocopherol absorption, metabolism, and transport in humans in vivo. Changes in food production in the United States and dietary intake impacted vitamin E availability and intake. Epidemiologic and therapeutic studies have pointed to its role in disease prevention and in healing processes. Specific molecular functions of alpha-tocopherol have been the most recent and surprising new findings and are an important area for future experimentation. Given the aging of the American population and the potential role for alpha-tocopherol in preventive medicine, the study of the molecular functions of vitamin E promises to provide some of the most exciting discoveries of the next decade.

Weight loss, weight maintenance, and improved cardiovascular risk factors after 2 years treatment with orlistat for obesity. European Orlistat Obesity Study Group

OBJECTIVE

To determine the effect of orlistat, a new lipase inhibitor, on long-term weight loss, to determine the extent to which orlistat treatment minimizes weight regain in a second year of treatment, and to assess the effects of orlistat on obesity-related risk factors.

RESEARCH METHODS AND PROCEDURES

This was a 2-year, multicenter, randomized, double-blind, placebo-controlled study. Obese patients (body mass index 28 to 43 kg/m2) were randomized to placebo or orlistat (60 or 120 mg) three times a day, combined with a hypocaloric diet during the first year and a weight maintenance diet in the second year of treatment to prevent weight regain. Changes in body weight, lipid profile, glycemic control, blood pressure, quality of life, safety, and tolerability were measured.

RESULTS

Orlistat-treated patients lost significantly more weight (p<0.001) than placebo-treated patients after Year 1 (6.6%, 8.6%, and 9.7% for the placebo, and orlistat 60 mg and 120 mg groups, respectively). During the second year, orlistat therapy produced less weight regain than placebo (p = 0.005 for orlistat 60 mg; p<0.001 for orlistat 120 mg). Several obesity-related risk factors improved significantly more with orlistat treatment than with placebo. Orlistat was generally well tolerated and only 6% of orlistat-treated patients withdrew because of adverse events. Orlistat leads to predictable gastrointestinal effects related to its mode of action, which were generally mild, transient, and self-limiting and usually occurred early during treatment.

DISCUSSION

Orlistat administered for 2 years promotes weight loss and minimizes weight regain. Additionally, orlistat therapy improves lipid profile, blood pressure, and quality of life.

Obesity and diabetes

Obesity, particularly truncal obesity, is closely correlated to the prevalence of diabetes and cardiovascular disease. Plasma leptin, tumour necrosis factor-alpha and non-esterified fatty acid levels are all elevated in obesity and play a role in causing insulin resistance. Diabetic glycaemic control and insulin resistance improve with reductions in obesity, but the treatment of obesity is difficult, and sustained weight reduction rarely occurs with dietary management alone. Hypocaloric diets should be combined with education and low-impact exercise, as well as behavioural techniques used to encourage long-term changes. Weight-reducing drugs have a role in the management of obesity but only as part of such a total package. Newer anti-obesity drugs such as orlistat and sibutramine are well tolerated and have been shown to improve glycaemic control in diabetes. It is probable that drugs developed in the future will act at different sites in the pathways regulating body weight, but they may have to be used in combination.

Current concepts in the pharmacological management of obesity

The pharmacological management of obesity has gained increasing attention as new weight loss treatments are approved and a significant proportion of the public strives to lose weight. Obesity is associated with a high mortality rate, multiple chronic medical conditions, and carries an enormous financial burden. Obesity is a multifactorial condition, most often due to an imbalance in energy intake and expenditure. Despite the greater focus on management of obesity, weight loss remains a difficult goal to achieve. Obesity is a chronic medical condition that may require long term treatment, therefore the risks and benefits of all pharmacological agents must be carefully considered. Noradrenergic appetite suppressants (ie. phenyl-propanolamine, phentermine) result in weight loss but stimulatory effects limit their use. The serotonergic agents (fenfluramine, dexfenfluramine) were effective weight loss drugs, but were voluntarily withdrawn from the US market last year because of cardiovascular and pulmonary complications. The combination noradrenergic/serotonergic agent sibutramine is indicated for the management of obesity, particularly in the presence of other cardiovascular risk factors. Modest weight loss is achieved with sibutramine, although weight gain is significant after discontinuation. In addition, long term safety data are not yet available. The thermogenic combination of ephedrine plus caffeine is minimally effective, and adverse effects are usually transient. Other thermogenic agents, such as beta3-agonists, are still under investigation. Agents may alter digestion through lipase inhibition (orlistat) or fat substitution (olestra). Orlistat decreases systemic absorption of dietary fat, decreasing body weight and cholesterol. Olestra is a fat substitute that has been incorporated into snack foods. Olestra substitution for dietary fat has not been studied as a weight loss strategy, although olestra has no caloric value and may be beneficial. The use of orlistat and olestra may be limited by gastrointestinal adverse effects. Finally, the manipulation of leptin and neuropeptide Y are under investigation for the treatment of obesity. Pharmacological agents should be used as an aid to a structured diet and exercise regimen in the treatment of obesity. Weight loss agents may result in initial weight loss, but sustained weight loss is not always achieved even with continuation of treatment. The effect of weight loss obtained while using pharmacotherapeutic agents on morbidity and mortality has not been established. Therefore, diet and exercise should be the focus of any weight loss programme. There is a continued need for safe and effective pharmacotherapeutic agents for the treatment of obesity.

Functional food science and defence against reactive oxidative species

This paper assesses critically the science base that underpins the argument that oxidative damage is a significant causative factor in the development of human diseases and that antioxidants are capable of preventing or ameliorating these disease processes. The assessment has been carried out under a number of headings, and some recommendations for future research are made based on the present day knowledge base. The knowledge database (1) Consideration of the basic science that underlies understanding of the role of free radicals in causing cellular pathologies, and the role of antioxidants in preventing this, shows that an imbalance of reactive oxygen species and antioxidant defence systems may lead to chemical modifications of biologically relevant macromolecules. This imbalance provides a logical pathobiochemical mechanism for the initiation and development of several disease states. Experimental data obtained in vivo provide evidence that antioxidants function in systems that scavenge reactive oxygen species and that these are relevant to what occurs in vivo. The relevance in vivo of these observations depends inter alia on knowledge of the uptake and distribution of the antioxidant within the human body, and on what tissue levels of the antioxidant may be expected in relation to dietary levels. (2) There is some way to go until validated precise methods are available for measuring biomarkers of oxidative damage in human subjects in vivo under minimally invasive conditions. With respect to oxidative damage in DNa, HPLC and GC-mass spectrophotometry methods have both merits and limitations. Lipid oxidation products in plasma are best measured as isoprostanes or as lipid hydroperoxides using specific HPLC techniques. Development of isoprostane measurement will advance specificity and precision. The measurement of oxidative damage to proteins has some potential but such methods have not been effectively exploited. (3) Epidemiological studies support the hypothesis that the major antioxidant nutrients vitamin E and vitamin C, and beta-carotene (which may or may not be acting as an antioxidant in vivo), may play a beneficial role in prevention of several chronic disorders. More research is needed on the impact of other non-nutrient compounds, such as other carotenoids and flavonoids, on human health. In general, human intervention studies using hard end-points are the gold standard. Trials are restricted mainly to the major antioxidants and do not allow firm conclusions because of inconsistent findings, an insufficient number of studies and the use of varying doses. There is evidence that large doses of beta-carotene may be deleterious to the health of certain subgroups of the population such as heavy habitual smokers. (4) With respect to the safety of administration of supplementary vitamins, vitamin C is safe at levels of supplementation up to 600 mg/d, and higher levels, up to 2000 mg/d, are without risk. Vitamin E has a very low human toxicity and an intake of 1000 mg/d is without risk; 3200 mg/d has been shown to be without any consistent risk. Large intakes of beta-carotene must be viewed with caution because they have been shown to confer detriment to a population at high risk of lung cancer when administered after many years of high risk (smoking) behaviour. Until further work clarifies the situation in heavy smokers with respect to taking supplements, larger doses should be avoided by such individuals. There is little reliable information about the human toxicology of flavonoids and related non-nutrient antioxidant constituents of the diet. (5) The food industry has long experience in the control of oxidative damage in foods and this experience can be used to advantage for the protection of food antioxidants which are beneficial. Some of these, such as vitamins C and E and beta-carotene, are well known, and strategies for their protection in foods are already exploited by food technologies. (ABSTRACT TRUNCATED)

Orlistat

Orlistat (tetrahydrolipstatin) is an inhibitor of pancreatic and other lipases. As a pancreatic lipase inhibitor, it acts in the gastrointestinal lumen and is indicated for use in obesity. Serum total cholesterol and low density lipoprotein-cholesterol levels were reduced in obese, but otherwise healthy, patients during < or = 2 years' orlistat treatment; serum triglyceride and high density and very low density lipoprotein-cholesterol levels were unchanged in trials of < or = 12 weeks. Obese patients who were maintained on a hypocaloric diet and who received orlistat 360 mg/day for 12 weeks lost a significantly greater percentage of bodyweight than placebo recipients (5 vs 3.5%). In 2-year studies, weight loss was significantly greater in orlistat than in placebo recipients by the end of year 1; weight was further reduced or maintained in the second year, when a eucaloric diet was allowed, in orlistat but not placebo recipients. A greater proportion of orlistat than placebo recipients lost > 5% or > 10% of their initial bodyweight in 1- and 2-year studies.

Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. European Multicentre Orlistat Study Group

BACKGROUND

We undertook a randomised controlled trial to assess the efficacy and tolerability of orlistat, a gastrointestinal lipase inhibitor, in promoting weight loss and preventing weight regain in obese patients over a 2-year period.

METHODS

743 patients (body-mass index 28-47 kg/m2), recruited at 15 European centres, entered a 4-week, single-blind, placebo lead-in period on a slightly hypocaloric diet (600 kcal/day deficit). 688 patients who completed the lead-in were assigned double-blind treatment with orlistat 120 mg (three times a day) or placebo for 1 year in conjunction with the hypocaloric diet. In a second 52-week double-blind period patients were reassigned orlistat or placebo with a weight maintenance (eucaloric) diet.

FINDINGS

From the start of lead-in to the end of year 1, the orlistat group lost, on average, more bodyweight than the placebo group (10.2% [10.3 kg] vs 6.1% [6.1 kg]; LSM difference 3.9 kg [p<0.001] from randomisation to the end of year 1). During year 2, patients who continued with orlistat regained, on average, half as much weight as those patients switched to placebo (p<0.001). Patients switched from placebo to orlistat lost an additional 0.9 kg during year 2, compared with a mean regain of 2.5 kg in patients who continued on placebo (p<0.001). Total cholesterol, low-density lipoprotein (LDL) cholesterol, LDL/high-density lipoprotein ratio, and concentrations of glucose and insulin decreased more in the orlistat group than in the placebo group. Gastrointestinal adverse events were more common in the orlistat group. Other adverse symptoms occurred at a similar frequency during both treatments.

INTERPRETATION

Orlistat taken with an appropriate diet promotes clinically significant weight loss and reduces weight regain in obese patients over a 2-year period. The use of orlistat beyond 2 years needs careful monitoring with respect to efficacy and adverse events.

Update on the pharmacotherapy of obesity

OBJECTIVE

To review recent developments in the pharmacotherapy of obesity, including the agents currently approved for use in the management of obesity and those under development.

DATA SOURCES

A MEDLINE search from January 1990 to July 1997 was conducted to identify English literature available on the pharmacotherapy of obesity. The search was supplemented by a review of the bibliographies of identified literature.

STUDY SELECTION

All controlled and uncontrolled trials were reviewed. When available, double-blind, placebo-controlled trials were used preferentially.

DATA EXTRACTION

Agents were reviewed with regard to mechanism of action, clinical trial data regarding efficacy, adverse effects, pharmacokinetics, drug interactions, and contraindications where information was available. Study design, selected population, results, and adverse effect information were included.

DATA SYNTHESIS

The anorexiants currently available or under development for the management of obesity regulate food intake and satiety via the adrenergic and/or serotonergic pathways. Clinical trials have shown a 10-15% weight loss can typically be anticipated; however, little long-term safety and efficacy data are available. Adverse events tend to be mild and self-limiting, but serious adverse events can occur. Treatment options under development include thermogenic agents, digestive inhibitors, and analogs and antagonists of hormones that regulate food intake and satiety.

CONCLUSIONS

Several mechanisms to control weight are currently under investigation for the management of obesity. Since obesity is a chronic condition, further studies should be conducted to evaluate the long-term safety and efficacy of these agents and the role of combination therapy using different modalities.